Power loss under acceleration

[Karter]

I just bought my first diesel truck last week. Its a 2006 QC 2500 4x4 with 133k. I've been reading on this forum about tons of stuff I wasn't aware of when I bought the truck, and now I'm wondering what I may have gotten myself into.

Under heavy acceleration, like getting on a highway while pulling a light trailer, I hear a single beep. Now I've also noticed that the "check gauges" light is dimly lit. There seems to be an overall lack of power under these conditions, although it seems fine when I'm not towing. Admittedly, I don't have a good baseline though since I just got the truck. I'm not even sure where to start with this problem.

Any ideas or suggestions where to start? Thanks.

 

[Missouri Mule]

Pretty sure the 3rd generations have "over boost condition" trouble code ( the 2nd gen with the 24 valve/vp44 pump did). That could be the beep and the check engine light. (boost= psi the turbo is putting out.) Don't know where the map sensor is on 3rd but on 2nd located on top intake manifold.

Used to be able to read codes on odometor by turning key on-off,on-off, on, in 5 second period.

 

[cerberusiam]

Get a code reader, or go to a parts store, and find out what the codes are. Too many things this could be without a little more info such as codes.

 

[Karter]

Okay, I bought a code reader. This is what it read.

P0234 TURBO OVERBOOST CONDITION - This looks like it could be something with the Wastegate. Now I just need to figure out what that looks like.

P1755 TRANSMISSION THROTTLE VALVE CONTROL

U1421 IMPLAUSIBLE IGNITION KEY OFF TIME *update* - I'm thinking this is likely because the my gauge cluster is currently not working properly. I'm waiting for a replacement to arrive.*

 

[Prairie Dog]

Check the vacuum line going to the turbo's waste gate. It may be disconnected or pinched by someone to get more boost. It could also have an adjustable boost elbow that's set for too high of boost.

 

[Karter]

Thanks Prairie Dog. I checked the line as best as I can and it looks okay. This truck was sitting on a dealer's lot in MN for a couple months in the winter when I bought it. I'm wondering if the waste gate isn't rusty or stuck as a result of sitting for so long? I sprayed WD-40 on the linkage, but I can't really get at it to pull it the rod off and see if it moves smoothly. I'm going to call a buddy with a hoist and see if we can get at it that way.

 

[cerberusiam]

Can the reader clear the codes? You need to clear them and see if they come back.

The over boost will defuel the engine so you loose top end power. You will need to get a boost gaauge on it and see what is happening to really figure things out. A boost fooler will get rid fo the code and help the mid range and top end power plus EGT's.

 

[Karter]

I'm clearing the codes now, but this code scanner has Freeze Frame and this is what it said for the last time the P0234 code came up.

Calc Load 73.3%
ECT 194F
MAP (in Hg) 75.3
Eng RPM 2565
Veh Speed MPH 57
IAT 102.2F
TPS 70.6%
Run Time (sec) 1384
Fuel Pres 17424.7psi
Fuel Level 18.8%
BARO (InHg) 27.8
ECU Volts 14.687
Ambient 62.6F

 

[cerberusiam]

The MAP reading would trigger the code, almost 37 psi. WG is definitely not opening at those levels or the MAP sensor is screwed up.

 

[Karter]

The MAP reading would trigger the code, almost 37 psi. WG is definitely not opening at those levels or the MAP sensor is screwed up.

What range should the MAP reading be in?

 

[Karter]

Do we know at what pressure the stock system will shut it down or scale back the fuel? Maybe this whole thing is simply a bad MAP sensor. I just checked the Freeze frame again after clearing everything out and running hard pulling a trailer and the new MAP reading is 75.3. It seems odd to me that the reading would be exactly the same as last time. None the other measured parameters are exactly the same?

 

[cerberusiam]

Like I said in previous post, could be the MAP is bad. The over boost is going to trigger around 33-34 psi of boost, at least that is what it did on my truck with a manual gauge.

The 75.3 might be th elimit of the MAP sensors capability to read, or, the limit of the boost tables. It depends whether that number is true MAP converted or boost table lookup. Don't know if the reader is adjusting for ambient pressure or not when it displays.

A manual boost gauge will tell you something about what is actually being displayed and what the real boost number is.

 

[Karter]

I'm definitely going to need to get a boost gauge.

 

[cerberusiam]

I'm definitely going to need to get a boost gauge.

With problems like these the old reliable mechanical gauges definitely are a bonus when trying to decipher the electronic readings. The basic gauges; boost, LP fuel pressure, rail pressure, EGT, and trans temp if an auto are almost mandatory if you want to troubleshoot it yourself.

 

[EDankievitch]

I had the Waste gate actuator wire chafe through and it threw a bunch of codes. I would check that first, Mine did not look bad at first, it had just a small nick in the wire. But the nick allowed salt in to the wire and the salt took out the wire inside the insulation. As for the transmission code check the kick down cable make sure some one didn't break it off at the throttle position control sensor. Oh wait you have an 06 the sensor might not be on the engine and there might not be a cable controlling the transmission.

 

[Karter]

Thanks for all the info everyone. I'm looking into a manual boost gauge right now. I'll also double check the wires.

 

[cerberusiam]

Definitely check the wires for the WG controler and the TTVA motor. The TTVA code could be a bad motro, bad connection, or even left over form when it was replaced. The WG controller is going to throw codes for it if the circuit goes open, goes low, or the actuator quits working. No codes except over boost if the actuator quits working correctly. Good luck.

 

[Karter]

Just a follow up to this thread since the problem is fixed. Turns out the wastegate was just stuck closed. As I mentioned, I bought this truck off a dealer in MN's lot where it had been sitting for a few months in the winter. I think it just was stuck. Put some WD40 on it and worked it back a forth a bit and it freed right up. Working perfectly now. On the plus side, I got a taste of what it would feel like with some extra boost.